Lubricating composition



Patented Nov. 28, 1933 UNITED STATES PATENT OFFICE 1,937,462 LUBRIOATING COMPOSITION N Drawing.

Application October 18,

Serial No. 227,059. Renewed May 1, 1933 6 Claims.

The present invention relates to a new useful lubricating composition and to the method of making the same, and more particularly to a method of raising the melting point and imparting a body to or stiffening the consistencyof petroleum. products known as mineral oils.

It has been the common practice in the manu facture of lubricants suitable for various uses in lubricating bearings or other friction surfaces to 10 add a sufficient quantity of soap to the mineral oil to give it the desired consistency, as well asto raise the melting point to the desired amount for the service to which the lubricating composition is to be put.

In such lubricating compositions, it is essential to have present a small percentage of water such as 3 or 4 percent to form an emulsion of the oil and soap to avoid separation of the oil from the large quantity of soap which is usually present in such compositions.

In service, however, the water or other ingredient which may be used to keep the soap and oil in emulsion frequently evaporates or is lost from the composition, due to the temperatures and speed of operation of the machine in which the composition is used. As some of the water or other emulsifying agents is lost, there is a tendency for the soap and oil to separate, thus permitting the oil which is of lower viscosity to seep away from the surfaces which are to be lubricated. Upon such separation, the soap which frequently is present in a large percentage in a lubricating composition may cake or form a gumlike residue which greatly increases the coeflicient of friction and causes a decrease in the efficiency of the machine. 3

An object of the present invention is to provide a lubricating composition in which the substances added to the mineral oil for stiffening the consistency and raising the melting point will not separate from the oil in service, and in which no water is used.

A further object of the invention is to provide a mineral composition composed of a lubricating oil with ingredients added to stiffen the consistency and raise the melting point in which the added ingredients are in solution in the oil.

An object of my invention is to produce a lubricating composition which is stable and homogeneous in character and in which the stiffness of the composition and the melting point thereof may be readily controlled by adding a minimum amount of ingredients to the mineral oil.

Another object of my invention is to produce a lubricating composition in which the ingredient added to stiffen or increase the viscosity of the composition is a hydro-carbon derivative which in itself has lubricating value and does not materially increase the coefficient of friction of the composition. 30

A further object isto provide amethod by which the consistency and melting point of a lubricating composition may be independently controlled by combining with a mineral oil in varying amounts two additional ingredients, one

serving to increase consistency and the other. serving to raise the melting point making it possible to utilize an oil of higher lubricating value where a relatively stiff lubricant'having a relatively high melting point is required and making 7 it possible to produce a lubricant of a given consistency and melting point from lubricating oils of different viscosities.

A further object of the present invention is to provide a lubricating composition which is substantially free from water and in which a relatively small amount of soap is added to the mineral oil for raising the'melting point,-and in which a relatively small amount of an anilid of a fatty acid is added to stifien the consistency, thus forming a lubricating composition which is stable and homogeneous in character and in which the substances added to the mineral oil will not separate from the oil in service.

For many uses lubricants are desirable in 35 which a mineral oil of a low viscosity may be used for its lubricating value and it is an object of my invention to so increase the viscosity and raise the melting point of such' a lubricating mineral oil that the lubricant will remain in the bearings or other metallic surfaces to be lubricated and cling to the metallic surface to be lubriicated even though such metallic surfaces in operation assume a relatively high temperature.

An object of my invention is to produce a lubricating composition having a relatively high content of a low viscosity mineral oil to which have been added compounds. to stiffen the consistency of the composition and raise the melting point of the composition to a desired degree for lubricating surfaces operated under heavy pressures or high temperatures, or both.

In providing a lubricant for bearings or other friction surfaces, it is often impossible to provide a pure mineral oil which is of the proper consistency and has the proper melting point, also the viscosity of an oil of the proper consistency may be so I igh as to greatly reduce its lubricating properties. As above explained, it has been common practice to add soap to provide a lubri higher melting point, but where a single ingredient such as soap is employed to change both the consistency and melting point, it is obvious that the melting point and consistency are dependent one on the other and in many instances the melting point will be higher or lower than desirable for the particular use to which the composition is to be put. It is usual that when soap is added to a lubricating oil to give the desired high melting point to the lubricating composition, suflicient soap must be added so that the mixture is thickened too much. This fact frequently necessitates the use of thinner lubricating oil or an oil of inferior lubricating quality than that which is otherwise desirable for the purpose intended in order to keep the consistency down to the desired degree for the composition. Furthermore, in orderto obtain a consistency and melting point approximating that most suitable for the particular use, it is often necessary to employ as a base an oil of inferior lubricating quality.

The present invention provides a method of obtaining lubricating compositions varying in consistency and melting point through a relatively wide range and in which the consistency and melting point are independently controlled by employing as constituents of the composition two different substances, one of which has the property of stiffening the consistency of the composition to a high degree as compared to its proportion in the composition and the other having the property of raising the melting point to a high degree as compared to its proportion in the composition, so that relatively small amounts of these substances added to the oil produce the desired results.

The oil employed in tne composition is preferably one of the products of'petroleum known as mineral oil since this oil is most commonly used for lubricating purposes and offers a wide range of selection as to properties of viscosity, consistency and melting point.

The substance employed for stiffening the consistency is preferably an amid of a fatty acid such as stearanilid, a small proportion of which serves to greatly stiffen the consistency of the composition and at the same time raises the melting point above that of a petroleum addition such as parafiin or wax. Anilids of other fatty acids such as oleic, arachidic, or palmitic, may also be used.

A further advantage of stearanilid or anilids of other fatty acids is that they are hydrocarbons and possess lubricating qualities themselves. The substance employedfor raising the melting-point is-preferably a metallic soap such as metallic salts of fatty acids or a mixture of such salts. Other soaps formed from vegetable or animal oils, such as lard oil, tallow, cottonseed oil, castor oil, and the like, may also be used to obtain the various desired characteristics of the lubricating composition. Sodium or calcium stearates in very small quantities increase the melting point considerably. Zinc stearate, while it does not increase the melting point to as great an extent as sodium or calcium stearates, is advantageous for the reason that it does not appreciably stiffen-the consistency of the composition and for the reason that its presence in the grease composition improves the quality thereof, enhancing the smoothness and spreading qualities. In view of these facts, 9. very small proportion of sodium or calcium stearate is used to-,

-cating composition of stiffer consistency and gether with a somewhat larger proportion of zinc stearate in order to obtain the required rise in melting point and also the advantageous effects of the zinc stearate.

In addition to its stiffening effect, the anilid has the property of increasing the solubility of soaps, so that the soaps are more readily dissolved and soaps which are normally insoluble such as calcium soaps may be readily dissolved in the composition. It has also been found that the presence of the anilid makes the composition more stable than a solution of soap in oil without the anilid so that the lubricating composition retains its original properties when subjected to repeated heating and cooling such as occurs when the lubricant is confined in the bearings of a machine.

It will be apparent that where it is desired to obtain a lubricating composition which differs but slightly in melting point and consistency from an oil of suitable lubricating value, it will be necessary to add very small quantities of the anilid and soap, and that, where greater variations are desired proportionately higher percentages of anilid and soap must be added. In all cases, however, the percentage of added ingredients is relatively small as compared to the percentage of soap usually added when soap alone is used as the agent to raise the melting point and stiffen the consistency. It will also be apparent that the relative percentages of the anilid and soap and of the soap constituents may be varied as desired to obtain the required consistency and melting point using an oil of any desired viscosity.

A composition suitable for lubricating machines having high speeds and low bearing pressure such as, for instance, the ball bearings of an electric motor, is as follows:

91.5% zero mineral oil having a viscosity of 500 Saybolt at F., 75% of sodium soap, 2.75% of zinc soap, and 5% of stearanilid.

It is to be understood that the proportion of the lubricating oil, soap, and the anilid may be varied in order to obtain the desired characteristics of the lubricating mixture, but in any event, in accordance with my invention the quantity of soap and anilid added to the lubricating oil is very small relative to the amount of soap commonly added to a lubricating oil in order to obtain a lubricating mixture or grease of the desired characteristics.

The viscosity of the oil most suitable-for the composition will vary with the speed at which the machine operates, but by varying the percentages of the anilid and soap, a composition having the desired consistency and melting point may be made using an oil of the desired viscosity.

When the anilid of a fatty acid and soap is added in accordance with my invention in the- For a lubricating composition in which great for.

stiffness is desired, it may be that the percentage 1 of lubricating oil may be as low as and 15% or more of stearanilid or an anilid of another suitable fatty acid may be used to greatly stiffen the consistency of the lubricating oil. Even in this case, however, a considerably smaller amount of soap is used than what would ordinarily be used without the use of an anilid of a fatty acid, and the desired stiffness of composition and the desired melting point of the lubricating composition may be obtained with a minimum amount of soap present.

It will be apparent that the present invention provides a method by which a lubricating composition may be made which possesses the properties most desirable for the particular use for which it is intended and that the composition may be varied to meet the requirements of any one of an infinite number of uses, as will be apparent to one skilled in the art to which the invention appertains.

What I claim is:

1. A lubricating composition consisting of a mineral oil to which has been added relatively small quantities of an amid of a fatty acid and a metallic soap, said amid serving to stiffen the consistency of the composition and said soap serving to increase the melting point thereof.

2. A lubricating composition consisting of a mineral oil to which has been added relatively small quantities of an anilid of a fatty acid and a metallic soap, said anilid serving to stiflen the a metallic soap in solution, and said composition being substantially free from water.

5. A stable, homogeneous and transparent lubricating composition consisting of a mineral oil and relatively small quantities of stearanilid and a metallic stearate in solution, said composition being substantially free from water.

6. A lubricating composition consisting of a mineral oil to which has been added a small quantity of an anilid of a fatty acid, and small quantitles of an alkali soap and a zinc soap, said composition being substantially free from water.

EDWARD A. NHL. 

